I registered a smallish, old boat trailer in Ca last year with no papers at all. I told them that it had been abandoned on my uncle's farm for at least 10 years and that he gave it to me. It went pretty smoothly because a vehicle gifted from a relative is less of a hassle and one that isn't coming from out of state is less of a hassle. Talk to your uncles and see if maybe they have a cat trailer exactly like yours sitting around that you can have.